Circuits and devices related to voltage conversion

ABSTRACT

Circuits and devices related to voltage conversion. In some embodiments, a voltage converter can include a voltage conversion circuit configured to convert an input voltage to an output voltage based on a drive signal, and a feedback circuit configured to generate an error signal based on the output voltage and a reference voltage. The voltage converter can further include a feedforward circuit configured to generate a feedforward signal indicative of a change opposite to that of a change in the input voltage. The voltage converter can further include a drive control circuit configured to generate the drive signal based on the feedforward signal and the error signal.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.15/095,020 filed Apr. 9, 2016, entitled VOLTAGE CONVERTER AND CONTROLMETHOD THEREOF, the benefit of the filing date of which is herebyclaimed and the disclosure of which is hereby expressly incorporated byreference herein in its entirety.

TECHNICAL FIELD

The present application relates to a field of electronic technique, moreparticularly, to a voltage converter and control method thereof.

BACKGROUND

Electronic apparatus typically include therein electronic modules suchas different subsystems, circuits, and so on. These electronic modulesusually require different supply voltages (e.g., 1.8 volts, 2.5 voltsetc.) for achieving normal operations. To ensure normal operations ofevery electronic module in electronic apparatus, a voltage converter istypically utilized to convert a DC voltage (e.g., a voltage from abattery) to another different DC voltage as required by every electronicmodule, that is, a specific input voltage Vin is converted into adifferent output voltage Vout.

In existing voltage converters, for example, electric energy at an inputis stored transitorily in an inductor and/or a capacitor (e.g., acharging process is performed), and thereafter the electric energy isreleased at a different voltage at an output (e.g., a dischargingprocess is performed), so that the input voltage Vin is converted intothe desired output voltage Vout. Accordingly, a drive signal is employedto drive a control device (e.g., a switch) in the voltage converter, bywhich the charging process and the discharging process are controlled soas to obtain the desired output voltage Vout. That is, a turn-on timeTon during which the switch is ON to charge and a turn-off time Toffduring which the switch is OFF to discharge are controlled. The turn-ontime Ton corresponds to the pulse width of the drive signal.

In the operation process of the voltage converter, the input voltage Vinusually is not fixed, and may generate jumping change. For example, inelectronic apparatus such as a mobile phone, a tablet computer, adigital camera etc., a battery therein has relatively large parasiticresistance. When a module (e.g., a flash drive, a RF module) in theelectronic apparatus, which requires very large current, is triggered,it may lead to an instant and significant drop for the output voltage ofthe battery. Therefore, it's desired that the voltage converter has verygood transient response characteristic, so that even if there is aninstant drop in the output voltage of the battery (corresponding to theinput voltage Vin of the voltage converter), the voltage converter canalso provide stable output voltage, allowing the electronic modulesdriven by the voltage converter to operate normally. The transientresponse characteristic of the voltage converter is closely related toits bandwidth. The larger the bandwidth is, the better the transientresponse characteristic is; the smaller the bandwidth is, the worse thetransient response characteristic is. Therefore, in order to enhance thetransient response characteristic of the voltage converter, it isdesirable to increase its bandwidth as much as possible. However, whenthe bandwidth has been increased to a certain extent, the parasitic zeropole at high frequency may be included within the bandwidth, which maymake a design of the frequency compensation become very complex anddifficult. In addition, as for a boost converter, there is aright-half-plane zero point at low frequency (about several hundredkHz), whose bandwidth has to be set within the right-half-plane zeropoint to meet the stability requirement, so it is hard to improve thetransient response of the boost converter. Hence, the applicationprovides an input voltage feedforward device, which may notably enhancethe transient response characteristic of the voltage converter as for acertain bandwidth.

SUMMARY

Aspects of the present disclosure may relate to a control device and acontrol method for a voltage converter, and the voltage converter, whichcan improve the transient response characteristic of the voltageconverter. Accordingly, it allows the output voltage to maintainfavorable linear state even if an input voltage changes.

A voltage converter according to an embodiment of the present disclosuremay comprise a voltage conversion circuit, a feedback circuit, a drivecontrol circuit and a feedforward circuit. The voltage conversioncircuit receives a drive signal from the drive control circuit, andconverts an input voltage to a desired output voltage based on the drivesignal. The feedback circuit compares the output voltage with areference voltage, and outputs an error signal. The error signal is usedfor indicating a difference between the output voltage and a targetvoltage to be output by the voltage converter. The feedforward circuitreceives the input voltage, and generates a feedforward signal for theinput voltage. The feedforward signal has a change opposite to that ofthe input voltage. The drive control generates the drive signal fordriving the voltage conversion circuit based on the feedforward signaland the error signal. The drive signal is provided to a control devicein the voltage conversion circuit for controlling charging anddischarging operations thereof.

A voltage conversion method according to an embodiment of the presentdisclosure may comprise: converting an input voltage to a desired outputvoltage by using a voltage conversion circuit; comparing the outputvoltage with a reference voltage, corresponding to a target voltage tobe output by the voltage converter, by using a feedback circuit, andoutputting an error signal; generating a feedforward signal for theinput voltage based on the input voltage by using a feedforward circuit,where the feedforward signal is a pulse signal having a changingtendency opposite to that of the input voltage; and generating a drivesignal for driving the voltage conversion circuit based on thefeedforward signal and error signal by using a drive control circuit.

In technical solutions of a control device and a control method for avoltage converter, and a voltage converter according to the embodimentsof the present disclosure, the transient response characteristic of thevoltage converter can be improved by setting an input voltagefeedforward circuit, by which a jumping change of an input voltage isquickly converted into a feedforward signal to control the operation ofthe voltage converter. Accordingly, it allows the output voltage tomaintain favorable linear state even if the input voltage changes.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly explain the technical solutions, drawingsreferenced in the description of embodiments or conventionaltechnologies are briefly introduced below. The drawings described beloware merely some embodiments of the present disclosure, from which aperson of ordinary skill in the art can also obtain other drawingsaccording to these drawings. Identical reference numerals typicallyindicate identical components throughout these drawings.

FIG. 1 is a block diagram schematically illustrating a conventionalvoltage converter.

FIG. 2 is a block diagram schematically illustrating a first voltageconverter according to an embodiment of the present disclosure.

FIG. 3 schematically illustrates an example implementation of thevoltage converter in FIG. 2.

FIG. 4 is a circuit diagram schematically illustrating an examplestructure of a feedforward circuit.

FIG. 5 is a circuit diagram schematically illustrating another examplestructure of a feedforward circuit.

FIG. 6 is a block diagram schematically illustrating a second voltageconverter according to an embodiment of the present disclosure.

FIG. 7A schematically illustrates a first example of the feedforwardvoltage dividing circuit in FIG. 6.

FIG. 7B schematically illustrates a second example of the feedforwardvoltage dividing circuit in FIG. 6.

FIG. 8 schematically illustrates an example implementation of the secondvoltage converter in FIG. 6.

FIGS. 9A-9D schematically illustrate simulation results of voltageconversion performed by the second voltage converter in FIG. 8.

FIG. 10 is a flowchart schematically illustrating a voltage conversionmethod according to an embodiment of the present disclosure.

FIG. 11 is a block diagram of a portable electronic device that includesa voltage converter having one or more features as described herein.

FIG. 12 illustrates a wireless device that can be a more specificexample of the portable electronic device of FIG. 11.

DETAILED DESCRIPTION

A voltage converter to which the present disclosure relates may be aboost converter, a buck converter, or a boost-buck converter etc. Thevoltage converter can be used to convert a supply voltage to one or morevoltages required by respective electronic module(s) in electronicapparatus. The electronic modules for example can be an RF amplifier, adisplay device, and so on. The electronic apparatus including electronicmodules for example can be a mobile phone, a tablet computer, a monitor,an e-book reader, a portable digital media player, and so on. Types ofthe voltage converter, electronics modules to which the power issupplied, and electronic apparatus to which it is applied do notconstitute limitations to the present disclosure.

A source and a drain of a transistor in the present disclosure can besymmetrical. Accordingly, the source and the drain of a transistor canbe interchangeable. In an embodiment of the present disclosure, in orderto distinguish two electrodes of a transistor except a gate, one iscalled a source and the other is called a drain. In the drawings, as fora P-type transistor, a signal input terminal is taken as a source and asignal output terminal is taken as a drain; as for an N-type transistor,a signal input terminal is taken as a drain and a signal output terminalis taken as a source. A P-type transistor is turned on upon a low levelat the gate and is turned off upon a high level at the gate. An N-typetransistor is turned on upon a high level at the gate and is turned offupon a low level at the gate. Unless explicitly noted, the transistorsin embodiments of the present disclosure may be implemented by any typeof transistors, including but not limited to thin film transistors.

FIG. 1 is a block diagram schematically illustrating a conventionalvoltage converter 100. The voltage converter 100 shown in FIG. 1converts an input voltage Vin to an output voltage Vout, which may beused for powering a load. As shown in FIG. 1, the voltage converter 100may comprise a voltage conversion circuit 110, a feedback circuit 120and a drive control circuit 130.

The voltage converter 100 in FIG. 1 is a buck conversion circuit. In thecase of a boost converter, the voltage conversion circuit 110 is a boostconversion circuit; in the case of a boost-buck converter, the voltageconversion circuit 110 is a boost-buck conversion circuit. The voltageconversion circuit 110 is used for converting an input voltage Vin intoa desired output voltage Vout.

The buck conversion circuit 110 in FIG. 1 comprises a transistor 101, adiode 102, an inductor 103 and a capacitor 104. The transistor 101operates under driving of the drive signal Sd to control charging anddischarging operations of the inductor 103. The inductor 103 is locatedbetween an output terminal of the transistor 101 and a port of theoutput voltage Vout, for performing charging and discharging operations.The diode 102 has a cathode connected to the input voltage Vin via thetransistor 101. And the diode 102 has an anode being grounded. Thecapacitor 104 is connected between the port of the output voltage Voutand the ground, for ensuring stable output of the output voltage Vout.

During the charging process, the transistor 101 is turned on, the diode102 is open, the inductor 103 is charged and the inductance current isgenerated; since the input voltage Vin is direct current (DC), aninductance current on the inductor 103 increases linearly in a certainrate, correspondingly, the current passes through two terminals of theload, so as to have the output voltage. During the discharging process,the transistor 101 is tuned off, the diode 102 is a short circuit, andbecause of a holding characteristic of the inductance current, thecurrent that passes through the inductor 103 will slowly decrease from avalue when the charging is completed, until a next charging processstarts or the current value drops to zero; correspondingly, the inductorL (103) starts to charge the capacitor C (104), thereby the outputvoltage Vout is maintained. In the voltage conversion circuit 110 inFIG. 1, the diode 102 may also be replaced with a transistor. Thealternative transistor is turned off during the charging process, andturned on during the discharging process. Correspondingly, the drivecontrol circuit 130 may generate a drive signal for the alternativetransistor. In this case, the control device includes both thetransistor 101 and the alternative transistor.

The feedback circuit 120 receives the output feedback (e.g., the outputvoltage Vout) of the voltage converter 100, compares it with a referencevoltage Vref that corresponds to a target voltage to be output, andoutputs an error signal Se. The feedback circuit 120 for example mayinclude a sampling circuit and an operation amplifier. The samplingcircuit is used to sample the output voltage Vout, and provide thesampled output voltage Vout to an input terminal of the operationamplifier. The operation amplifier includes two input terminals and oneoutput terminal. One input terminal receives the output from thesampling circuit, the other input terminal receives the referencevoltage Vref, and outputs the error signal Se that represents adifference between the real output voltage of the voltage converter 100and its target output voltage.

The drive control circuit 130 generates a drive signal Sd for drivingthe transistor 101 according to an error signal Se output by thefeedback circuit 120, to obtain a desired output voltage Vout. The drivecontrol circuit 130 may for example include a frequency compensationcircuit and a pulse width modulation (PWM) circuit. The frequencycompensation circuit implements frequency compensation for the errorsignal Se to make it not vibrate, thereby ensuring a stable output. ThePWM circuit implements pulse width modulation to the output of thefrequency compensation circuit, so as to output a PWM pulse as a drivesignal Sd. The drive signal Sd is used for driving operations of thetransistor 101.

The feedback circuit 120 and the drive control circuit 130 form anegative feedback loop, which allows the output voltage Vout of thevoltage converter 100 to stably correspond to the target output voltage.

In the voltage converter 100 shown in FIG. 1, a PWM pulse is used forcontrolling operations of the voltage conversion circuit 110. When theinput voltage Vin changes in a jumping manner, the PWM pulse may not beimmediately adjusted with the change of the input voltage Vin, so as toquickly adjust the operation status of the voltage converter 100. Whenthe input voltage Vin changes in a jumping manner, a certain range offluctuation occurs in the output voltage Vout. Only if the fluctuatingoutput of the output voltage Vout has passed through the feedback loopand been sampled and adjusted, the output voltage Vout of the voltageconverter 100 may restore to the voltage before the fluctuation.Therefore, when the input voltage Vin changes in a jumping manner,fluctuation is generated in the output voltage Vout, and the outputvoltage Vout may make response to the input voltage Vin only if it hasbeen adjusted by the feedback loop, and such process shows hysteresis.

As to the voltage converter in a current mode, when the input voltageVin changes, the sampling current of the output current may form acurrent loop, and immediately change so as to adjust a duty cycle of thevoltage conversion circuit 110, so as to adjust the output voltage. Thecurrent loop can reduce the hysteresis to a certain extent, but thecurrent loop needs to implement slope compensation to prevent thevoltage converter from generating secondary slope oscillation. Moreover,when the input voltage Vin changes greatly, it is typically necessary toincrease the compensation value of the slope compensation. Accordingly,when a sawtooth waveform signal is obtained by adding the samplingcurrent and the slope compensation signal, the sawtooth waveform signaldetermines a duty cycle of the voltage conversion circuit 110. It maygreatly weaken adjustment function of the current loop such that thesampling current signal takes up a rather small portion in the sawtoothwaveform signal.

In an embodiment of the present disclosure, a feedback circuit for theinput voltage Vin is set, by which the jumping change of the inputvoltage Vin is quickly converted into a feedforward signal to controlthe operation of the voltage converter, and the transient responsecharacteristic of the voltage converter can be improved. Accordingly, itallows the output voltage to maintain favorable linear state even if theinput voltage changes.

FIG. 2 is a block diagram schematically illustrating a first example ofa voltage converter 200 according to an embodiment of the presentdisclosure. As shown in FIG. 2, the voltage converter 200 may include avoltage conversion circuit 210, a feedback circuit 220, a drive controlcircuit 230 and a feedforward circuit 240.

The voltage conversion circuit 210 can be configured to receive a drivesignal Sd from the drive control circuit 230, and converts an inputvoltage Vin into a desired output voltage Vout based on the drive signalSd. The voltage conversion circuit 210 may be anyone of a buckconversion circuit, a boost conversion circuit or a boost-buckconversion circuit. In the case of a buck conversion circuit, thevoltage conversion circuit 210 may have a structure similar to that ofthe voltage conversion circuit 110 described herein in reference to FIG.1.

In the case where the voltage conversion circuit 210 is a boostconversion circuit, the output voltage Vout is higher than the inputvoltage Vin; in the case that the voltage conversion circuit 210 is abuck conversion circuit, the output voltage Vout is lower than the inputvoltage Vin; in the case that the voltage conversion circuit 210 is aboost-buck conversion circuit, the output voltage Vout may be higher orlower than the input voltage Vin.

The feedback circuit 220 can be configured to compare the output voltageVout with a reference Vref, and output an error signal Se. The referencevoltage Vref corresponds to a target voltage to be output by the voltageconverter 200. The feedback circuit 220 can correspond to the feedbackcircuit 120 in FIG. 1, and may for example include a sampling circuitand an operation amplifier. Furthermore, the feedback circuit 220 mayalso be implemented by a voltage divider and an operation amplifier. Thevoltage divider is used for taking a portion of the output voltage Vout,for example taking 1/10 of the output voltage Vout, and the taken outputvoltage can be compared with a reference voltage Vref to output an errorsignal Se. The error signal Se is used for indicating the differencebetween the output voltage Vout and a target voltage to be output by thevoltage converter 200.

The feedforward circuit 240 can be configured to receive the inputvoltage Vin, and generate a feedforward signal Sf for the input voltageVin. When the input voltage Vin changes, the feedforward signal Sf canhave a change opposite to that of the input voltage Vin. For example,when the input voltage increases from a first voltage to a secondvoltage, the feedforward signal Sf may change from high to low; when theinput voltage decreases from a second voltage to a first voltage, thefeedforward signal Sf may change from low to high. When the inputvoltage Vin stays stable, the feedforward circuit 240 outputs a stablefeedforward signal Sf.

The drive control circuit 230 is in communication with the feedforwardcircuit 240 and the feedback circuit 220. The drive control circuit 230can be configured to receive a feedforward signal Sf from thefeedforward circuit 240, and receive an error signal Se from thefeedback circuit 220. The drive control circuit 230 can be configured togenerate a drive signal Sd for driving the voltage conversion circuit210 based on the feedforward signal Sf and the error signal Se. Thedrive signal Sd is provided to a control device for controlling thecharging and discharging operation in the voltage conversion circuit210. The control device can be different with different voltageconversion circuit 210. For example, in the voltage conversion circuit110 shown in FIG. 1, the control device is a transistor 101, to whichthe drive signal Sd is provided.

In the case where the first voltage converter 220 operates in a voltagemode, the drive control circuit 230 may for example include a frequencycompensation circuit and a pulse width modulation PWM circuit. Thefrequency compensation circuit implements frequency compensation for theerror signal Se and the feedforward signal Sf to make them not vibrate,thereby ensuring a stable output. The PWM circuit implements pulse widthmodulation to the output of the frequency compensation circuit so as tooutput a PWM pulse as a drive signal Sd. For examples, the drive signalSd is used for driving operations of the transistor 101 in FIG. 1. Inthe case where the first voltage converter 220 operates in a currentmode, the drive control circuit 230 can further include a slopecompensation circuit. The slope compensation circuit is used for sensingthe output current in the voltage conversion circuit 210, implementsslope compensation to the sensed current, and provides theslope-compensated current to the PWM circuit for pulse width modulation,so as to output a drive signal Sd.

The feedback circuit 220 and the drive control circuit 230 form anegative feedback loop, which makes the output voltage Vout of thevoltage converter 200 to stably correspond to a target output voltage.In the example of FIG. 2, the feedback circuit 220 and the feedforwardcircuit 240 can form a feedforward loop, which makes the voltageconverter 200 to output a stable output voltage Vout even if the inputvoltage Vin of the voltage converter 200 changes.

The structure of the voltage converter 200 in FIG. 2 is merely anexample. In some embodiments, the voltage converter 200 may furtherinclude other circuits, such as a mode control circuit, an oscillator,and so on. The mode control circuit for example can control theoperation of the voltage conversion circuit 210 in different modes. Theoperation mode may for example include a continuous control mode, adiscontinuous control mode etc.

In the voltage converter 200 according to an embodiment of the presentdisclosure shown in FIG. 2, a feedforward circuit 240 for the inputvoltage Vin is set, by which the jumping change of the input voltage Vinis quickly converted into a feedforward signal for controlling theoperation of the voltage converter 200. The transient responsecharacteristic of the voltage converter is improved. Accordingly, itallows the output voltage to maintain favorable linear state even if theinput voltage changes.

FIG. 3 schematically illustrates a first example of the voltageconverter 200 in FIG. 2. The voltage converter in FIG. 3 is a boostconverter. The boost converter may include a voltage conversion circuit210, a feedback circuit 220, a drive control circuit 230 and afeedforward circuit 240.

As shown in FIG. 3, the voltage conversion circuit 210 may include aninductor 211, a transistor 212, a diode 213 and a capacitor 214. Theinductor 211 receives the input voltage Vin, and is connected to theground via the transistor 212. The inductor 211 is charged during aturn-on time Ton and discharged during a turn-off time Toff. Thecapacitor 214 has one terminal connected to a connection point of theinductor 211 and the transistor 212 via the diode 213, and the otherterminal of the capacitor 214 is grounded. The capacitor 214 is used forensuring stable output of the output voltage Vout. The transistor 212controls the conversion operation of the voltage conversion circuit 210by being driven by the drive signal Sd output from the drive controlcircuit 230. During the charging process, the transistor 212 is turnedon, and the diode 213 is off. During the discharging process, thetransistor 212 is turned off, and the diode 213 is on. The transistor212 is a control device of the boost converter. The voltage conversioncircuit 210 shown in FIG. 3 is an example, which may further have otherstructure. For example, the diode 213 may be replaced with a transistor,which is controlled to be turned on and turned off by a drive signal Sd.

The voltage conversion circuit 210 in FIG. 3 receives the drive signalSd from the drive control circuit 230, and converts the input voltageVin into the desired output voltage Vout based on the drive signal Sd.

The feedback circuit 220 in FIG. 3 compares the output voltage Vout witha reference voltage Vref, and outputs an error signal Se. As shown inFIG. 3, the feedback circuit 220 includes a voltage divider 221 and anoperation amplifier (EA) 222. The voltage divider 221 is used for takinga portion of the output voltage Vout, and provides the taken outputvoltage to the operation amplifier 222. The operation amplifier 222 alsoreceives a reference voltage Vref along with the output from the voltagedivider 221. The operation amplifier 222 compares the output from thevoltage divider 221 with the reference voltage Vref to output the errorsignal Se. The error signal Se is used to indicate the differencebetween the output voltage Vout and a target voltage to be output by thevoltage converter 200.

The drive control circuit 230 in FIG. 3 receives a feedforward signal Sffrom the feedforward circuit 240, receives an error signal Se from thefeedback signal circuit 220, and then generates the drive signal Sd fordriving the voltage conversion circuit 210 based on the feedforwardsignal Sf and the error signal Se. The drive signal Sd is provided to acontrol device for controlling the charging and discharging process inthe voltage conversion circuit 210. As shown in FIG. 3, the drivecontrol circuit 230 includes an adder 231, a frequency compensationcircuit 232, a PWM circuit 233 and a drive circuit 234.

The adder 231 adds the feedforward signal Sf from the feedforwardcircuit 240 and the error signal Se from the feedback circuit 220. Thefrequency compensation circuit 232 implements frequency compensation forthe output (e.g., the sum of the error signal Se and the feedforwardsignal Sf) of the adder 231 and obtains a compensation signal COMP, tomake it not vibrate, and thus a stable output is ensured. The PWMcircuit 230 implements pulse width modulation to the output from thefrequency compensation circuit 232, and obtains a PWM signal. The drivecircuit 234 generates a drive signal for driving the control device inthe voltage conversion circuit 210 based on the PWM signal. For example,in the structure of the voltage conversion circuit shown in FIG. 3, thedrive circuit 234 generates a drive signal for driving the transistor212 based on the PWM signal. In the case where the diode 213 in FIG. 3is replaced with a transistor, the drive circuit 234 generates a drivesignal for driving the transistor 212 and the transistor (for replacingthe diode 213) based on the PWM signal.

The structure of the drive control circuit 230 shown in FIG. 3 is anexample, and may add other devices or omit devices therein as necessary.For example, in the case where the feedforward signal Sf and the errorsignal Se have stable phases, the drive control circuit 230 may notinclude the frequency compensation circuit 232. In another example, inthe case where the control device in the voltage conversion circuit 210is one transistor, it is also possible to drive the control devicedirectly by using the PWM circuit 233, thereby omitting the drivecircuit 234.

The feedforward circuit 240 receives the input voltage Vin and generatesa feedforward signal Sf for the input voltage Vin. As described above,when the input voltage Vin changes, the feedforward signal Sf has anchange opposite to that of the input voltage Vin; when the input voltageVin stays stable, the feedforward circuit 240 outputs a stablefeedforward signal Sf.

FIG. 4 is a circuit diagram schematically illustrating an examplestructure of the feedforward circuit 240 in FIG. 3. As shown in FIG. 4,the feedforward circuit 240 may include P-type transistors TP1 and TP2,N-type transistors TN1 and TN3, capacitors C1 and C2, and currentsources Is1 and Is2. P-type transistors TP1 and TP2 form a currentmirror. N-type transistors TN1 and TN3 form a current mirror. Theconnection structure of the devices in FIG. 4 will be described below.

A source of the transistor TP1 is connected to the first power voltageVdd. A drain of the transistor TP1 is connected to a drain of thetransistor TN1, forming the output terminal of the feedforward circuit240 to output a feedforward signal Sf. A gate of the transistor TP1 isconnected to a gate of the transistor TP2. A source of the transistorTP2 is connected to the first power voltage Vdd. A drain of thetransistor TP2 is connected to its gate, and also connected to a secondterminal of the capacitor C1. The connection point between the secondterminal of the capacitor C1 and the drain and gate of the transistorTP2 is denoted as node A. A first terminal of the capacitor C1 isconnected to the input voltage Vin. The first terminal of the capacitorC2 is connected to the input voltage Vin. The second terminal of thecapacitor C2 is connected to the output terminal of the current sourceIs1. An input terminal of the current source Is1 is connected to thefirst power voltage Vdd. A connection point between the output terminalof the current source Is1 and the capacitor C2 is denoted as node B. Thecurrent source Is2 is connected between node A and the second powervoltage Vss. An input terminal of the current source Is2 is connected tonode A. An output terminal of the current source Is2 is connected to thesecond power voltage Vss. A source of the transistor TN1 is connected tothe second power voltage Vss. A gate of the transistor TN1 is connectedto a gate of the transistor TN3. A drain of the transistor TN3 isconnected the node B. A source of the transistor TN3 is connected thesecond power voltage Vss.

In FIG. 4, the transistors TP1 and TP2 are connected to form a currentmirror structure. In order that a jumping change from high to low of theinput voltage Vin can change a current flowing through the transistorsTP1 and TP2, the source of the transistor TP1 and the source of thetransistor TP2 can be connected to a first power voltage Vdd higher thanVin. For example, the output voltage Vout may be used as the first powervoltage Vdd. The second power voltage Vss typically is a ground voltage.The transistor TN1 and TN3 are connected to form a current mirrorstructure.

In the case where the input voltage has no change, the current sourceIs1 makes the node B generate a voltage, which is for example equal tothe offset voltage of the transistor TN3. The voltage at the node B putsthe transistor TN3 in a weak turn-on state, and the transistor TN1, withwhich the transistor TN3 forms a current mirror, is also in a weakturn-on state. In the transistor TN1 which is in the weak turn-on state,there is for example a current of tens of nanoamps. Similarly, thecurrent source Is2 generates a voltage at the node A, which is forexample equal to a difference between the first power voltage Vdd and anoffset voltage Vgs of the transistor TP2, that is (Vdd−Vgs). The voltageat the node A puts the transistor TP2 in a weak turn-on state, and thetransistor TP1, with which the transistor TP2 forms a current mirror, isalso in a weak turn-on state. In the transistor TP1 which is in a weakturn-on state, there is also for example a current of tens of nanoamps.The weak turn-on state in the present disclosure can include a conditionwhere a transistor is on, but close to a turn-off state, such that atransistor may respond quickly to a change of the input voltage Vin, andthe transistor itself may not consume too much energy.

When the input voltage Vin changes from high to low, the voltage at thenode A is pulled down under a function of the capacitor C1, and acurrent flowing through the transistor TP2 is increased. Accordingly, acurrent flowing through the transistor TP1 is increased. Therefore, whenthe input voltage Vin changes from high to low, an outflowing currentsignal, i.e. a feedforward signal Sf, is generated along a path from thecapacitor C1 to the transistor TP2 and to the transistor TP1. Under afunction of the feedforward signal Sf, a voltage of the compensationsignal COMP in the drive control circuit 230 is raised immediately orsufficiently rapidly. A duty cycle of the drive signal Sd output by thedrive control circuit 230 is increased, making a current of the inductor211 in the voltage conversion circuit 210 increase quickly. The currentincrease of the inductor 211 makes the input power of the voltageconverter quickly increase to a value before the input voltage Vin isdecreased, thereby reducing the decrease of the output voltage caused bythe decrease of the input voltage Vin.

When the input voltage Vin changes from low to high, under a function ofthe capacitor C2, the voltage at the node B is increased, and a currentflowing through the transistor TN3 increases. Since the transistors TN1and TN3 form a current mirror, a current flowing through the transistorTN1 is increased. Therefore, when the input voltage Vin changes from lowto high, an inward discharging current signal, i.e. a feedforward signalSf, is generated through a path from the capacitor C2 to the transistorTN3 and to the transistor TN1. Under a function of the feedforwardsignal Sf, a voltage of the compensation signal COMP in the drivecontrol circuit 230 is immediately or sufficiently rapidly decreased.The duty cycle of the drive signal Sd output by the drive controlcircuit 230 is lowered, which reduces a current of the inductor 211 inthe voltage conversion circuit 210 quickly. The current reduction of theinductor 211 makes the input power of the voltage converter quicklydecrease to a value before the input voltage Vin is increased, therebyreducing the increase of the output voltage caused by the increase ofthe input voltage Vin.

In FIG. 4, the change of the feedforward signal Sf caused by the changeof the input voltage Vin is proportional to a quantity and a rate of thechange in the input voltage Vin. Therefore, the feedforward circuit 240in FIG. 4 may properly adjust an amplitude and a rate of the change ofthe compensation signal COMP in the drive control circuit 230 accordingto the change of the input voltage Vin. Accordingly, the feedforwardcircuit 240 allows the output voltage to maintain favorable linear stateeven if the input voltage changes.

When the input voltage Vin changes from low to high, the capacitor C2,the current source Is1, the transistor TN3 and the transistor TN1 worktogether to restrain a fluctuation of the output voltage Vout caused bythe change from low to high. When the input voltage Vin changes fromhigh to low, the capacitor C1, the current source Is2, the transistorTP2 and the transistor TP1 work together to restrain a fluctuation ofthe output voltage Vout caused by the change from high to low.Accordingly, when the input voltage Vin does not change from high tolow, the capacitor C1, the current source Is2, the transistor TP2 andthe transistor TP1 may be omitted from the feedforward circuit; when theinput voltage Vin does not change from low to high, the capacitor C2,the current source Is1, the transistor TN3 and the transistor TN1 may beomitted from the feedforward circuit.

When there is no change in the input voltage Vin, the current source Is1puts the transistor TN1 in a weak turn-on state. Thus, when the inputvoltage Vin changes from low to high, the transistor TN3 and TN1 canrespond quickly to generate a feedforward signal Sf. Therefore, thecurrent source Is1 speeds up a response speed of the feedforward circuit240 to the input voltage Vin. When it is unnecessary for the feedforwardcircuit to quickly respond to the change of the input voltage Vin, forexample when the input voltage Vin changes slowly from low to high, thecurrent source Is1 may be omitted. Similarly, when there is no change inthe input voltage Vin, the current source Is2 puts the transistor TP1 ina weak turn-on state. Thus, when the input voltage Vin changes from highto low, the transistor TP2 and TP1 can respond quickly to generate afeedforward signal Sf. Therefore, the current source Is1 speeds up theresponse rate of the feedforward circuit 240 to the input voltage Vin.When it is unnecessary for the feedforward circuit 240 to quicklyrespond to the change of the input voltage Vin, for example when theinput voltage Vin changes slowly from high to low, the current sourceIs2 may be omitted.

FIG. 5 is a circuit diagram schematically illustrating another examplestructure of a feedforward circuit 240 in FIG. 3. In FIG. 5, the samereference numerals are adopted for the same devices as in FIG. 4. TheP-type transistors TP1 and TP2, the N-type transistors TN1 and TN2, thecapacitors C1 and C2 are respectively identical to those in FIG. 4, andcan be referred to the connection relationship and functions describedin reference to FIG. 4.

FIG. 5 differs from FIG. 4 in that the feedforward circuit 240 in FIG. 5includes P-type transistors TP3 and TP4, N-type transistors TN2, TN4 andTN5, and a current source Is3, which replace the current sources Is1 andIs2 in FIG. 4. In FIG. 5, the P-type transistor TP3 and TP4 form acurrent mirror structure, and the N-type transistor TN4 and TN5 form acurrent mirror structure.

A source of the transistor TP3 is connected to the first power voltageVdd. A drain of the transistor TP3 is connected to the node B. A gate ofthe transistor TP3 is connected to a gate of the transistor TP4. Asource the transistor TP4 is connected to the first power voltage Vdd. Adrain of the transistor TP4 is connected to a source of the transistorTN4. The source of the transistor TN4 is connected to a second powervoltage Vss. A gate of the transistor TN4 is connected to a gate of thetransistor TN5. A drain of the transistor TN5 is connected to its gate,and connected to the first power voltage Vdd via the current source Is3.A drain of the transistor TN5 is connected to the second power voltageVss. A drain of the transistor TN2 is connected to the node A. A gate ofthe transistor TN2 is connected to a gate of the transistor TN5. Asource of the transistor TN2 is connected to the second power voltageVss.

In FIG. 5, the current source Is3 puts the transistor TN5 in an offsetstate, and the transistor TN4, with which TN5 forms a current mirror, isweakly turned on, which weakly turns on the transistor TP4 and TP3,thereby generating a voltage at the node B (e.g., equal to the offsetvoltage of the transistor). Furthermore, the transistor TN5 in an offsetstate typically puts the transistor TN2 in a weak turn-on state, andgenerates a voltage at the node A. The voltage at the node A is forexample equal to a difference between the first power voltage Vdd and anoffset voltage Vgs of the transistor, i.e. (Vdd−Vgs). Therefore, thetransistors TP3, TP4, TN2, TN4 and TN5, and the current source Is3 inFIG. 5 make a voltage generated respectively at the node A and node B inthe feedforward circuit 240, thereby making it possible to quicklygenerate a feedforward signal Sf when the input voltage Vin changes.

Similar to that in FIG. 4, in a situation when there is no change in theinput voltage Vin, a voltage at the node B puts the transistors TN3 andTN4 in a weak turn-on state; a voltage at the node A puts the transistorTP2 and TP1 in a weak turn-on state. When the input voltage Vin changesfrom high to low, the voltage at the node A is pulled down under afunction of the capacitor C1, and a current flowing through thetransistor TP1 and TP2 increases, thereby an outflowing current signalis generated at the output terminal of the feedforward circuit 240, i.e.a feedforward signal Sf. The feedforward signal Sf quickly increases thecurrent of the inductor 211 in the voltage conversion circuit 210, so asto reduce the decrease of the output voltage caused by the decrease ofthe input voltage Vin. When the input voltage Vin changes from low tohigh, under the function of the capacitor C2, the voltage at the node Bis raised, and a current flowing through the transistors TN3 and TN1increases, thereby an inward discharging current signal is generated atthe output terminal of the feedforward circuit 240, i.e. a feedforwardsignal Sf. The feedforward signal Sf quickly decreases the current ofthe inductor 211 in the voltage conversion circuit 210, so as to reducethe increase of the output voltage caused by the increase of the inputvoltage Vin.

FIG. 6 is a block diagram schematically illustrating a second example ofa voltage converter 600 according to an embodiment of the presentdisclosure. In FIG. 6, the same circuits and devices as those in FIG. 2are denoted with the same reference numerals, and can be referred to theabove description in reference to FIGS. 2-5. Compared with the firstexample voltage converter 200 in FIG. 2, a current adjustment circuit250 and a feedforward voltage dividing circuit 260 are added in thesecond example voltage converter 600 in FIG. 6.

The current adjustment circuit 250 makes the voltage converter 600 ofFIG. 6 operate in a current mode. However, the voltage converter 200 inFIG. 2 operates in a voltage mode. The current adjustment circuit 250 isused for sensing an inductance current in the voltage conversion circuit210, generates an indication signal Sc for indicating the inductancecurrent based on the sensed inductance current, and provides theindication signal Sc to the drive control circuit 230. The inductancecurrent in the voltage conversion circuit 210 directly affects theoutput voltage of the second voltage converter 600, thus the indicationsignal Sc for indicating the inductance current can be used for drivinga control device in the voltage converter, so as to obtain a desiredoutput voltage Vout.

The drive control circuit 230 generates a drive signal Sd for drivingthe voltage conversion circuit 210 based on the error signal Se from thefeedback circuit 220, the feedforward signal Sf from the feedforwardcircuit 240 and the indication signal Sc from the current adjustmentcircuit 250. The drive signal Sd is provided to a control device forcontrolling the charging and discharging operation in the voltageconversion circuit 210.

In the case where the voltage conversion circuit 210 in the voltageconverter 600 of FIG. 6 is a buck conversion circuit or a boost-buckconversion circuit, the output voltage Vout may be lower than the inputvoltage Vin. In this case, the feedforward circuit 240 may be unable todetect the voltage value of the input voltage Vin, thereby unable tooperate. Thus, a feedforward voltage dividing circuit 260 may be setbefore the feedforward circuit 240. The feedforward voltage dividingcircuit 260 divides the input voltage Vin and obtains a reduced voltageVin_div which is lower than the input voltage Vin, and then provides thereduced voltage Vin_div to the feedforward circuit 240. It should benoted that in the case of adopting the feedforward voltage dividingcircuit 260, the input voltage Vin located between the capacitor C1 andthe capacitor C2 in FIG. 4 and FIG. 5 is replaced with the reducedvoltage Vin_div.

FIG. 7A schematically illustrates a first example of the feedforwardvoltage dividing circuit in FIG. 6. The feedforward voltage dividingcircuit in FIG. 7A is a capacitive voltage dividing circuit. Thecapacitive voltage dividing circuit includes two capacitors C71 and C72connected in series. A first terminal of the capacitor C71 is connectedto the input voltage Vin. A second terminal of the capacitor C71 isconnected to a first terminal of the capacitor C72, and the reducedvoltage Vin_div is led out at a connection node between the capacitorC71 and the capacitor C72. A second terminal of the capacitor C72 isconnected to a ground. The reduced voltage Vin_div may be obtained by afollowing Equation (1):

$\begin{matrix}{{Vin\_ div} = {{Vin} \times {\frac{C\; 71}{{C\; 71} + {C\; 72}}.}}} & {{Equation}\mspace{14mu} (1)}\end{matrix}$

That is to say, a ratio of the reduced voltage Vin_div to the inputvoltage is equal to a ratio of a capacitance value of the capacitor C71to a sum of the capacitance value of the capacitor C71 and a capacitancevalue of C72.

FIG. 7B schematically illustrates a second example of the feedforwardvoltage dividing circuit in FIG. 6. The voltage dividing circuit in FIG.7B is a resistive voltage dividing circuit. The resistive voltagedividing circuit includes two resistors R71 and R72 connected in series.A first terminal of the resistor R71 is connected to the input voltageVin. A second terminal of the resistor R71 is connected to a firstterminal of the resistor R72, and the reduced voltage Vin_div is led outat a connection node between the resistors R71 and R72. A secondterminal of the resistor R72 is connected to a ground. The reducedvoltage Vin_div may be obtained by the following Equation (2):

$\begin{matrix}{{Vin\_ div} = {{Vin} \times {\frac{R\; 72}{{R\; 71} + {R\; 72}}.}}} & {{Equation}\mspace{14mu} (2)}\end{matrix}$

That is to say, a ratio of the reduced voltage Vin_div to the inputvoltage is equal to a ratio of a resistance value of the resistor R71 toa sum of the resistance of the resistor R71 and a resistance value ofR72. It should be noted that the voltage divider 221 in the feedbackcircuit 220 in FIG. 3 may be implemented by using any of the circuits inFIG. 7A and FIG. 7B.

FIG. 8 schematically illustrates a more specific example implementationof the voltage converter 600 of FIG. 6. In FIG. 8, circuits and devicesthe same as those in FIG. 3 are denoted with the same referencenumerals, and can be referred to the descriptions in connection withFIGS. 3-5. The voltage conversion circuit 210 in FIG. 8 is a boostconverter, which is the same as that in FIG. 3. Accordingly, nofeedforward voltage dividing circuit 260 has been set in FIG. 8.

The voltage converter in FIG. 8 is a converter operating in a currentmode, whereas the voltage converter in FIG. 3 is a converter operatingin a voltage mode. Accordingly, compared with FIG. 3, a currentadjustment circuit 250 is added into the voltage converter in FIG. 8.

The current adjustment circuit 250 is used for sensing an inductancecurrent in the voltage conversion circuit 210, generating an indicationsignal Sc for indicating the inductance current and providing it to thedrive control circuit 230. As shown in FIG. 8, the current adjustmentcircuit 250 includes a current sensing circuit 251, a slope compensationcircuit 252 and an adder 253.

The current sensing circuit 251 is connected to the inductor 211 in thevoltage conversion circuit 210, and used for sensing an inductancecurrent flowing through the inductor 211. The slope compensation circuit252 is used for generating a slop compensation signal, which canimplement slop compensation for the sensed inductance current to avoidgenerating secondary slope oscillation in the voltage converter 600.Thereafter, the inductance current sensed by the current sensing circuit251 is added to the slope compensation signal generated by the slopecompensation circuit 252 by the adder 253, so as to generate aslope-compensated inductance current. The slope-compensated inductancecurrent is for example a sawtooth waveform signal. The sawtooth waveformsignal determines a duty cycle of the voltage conversion circuit 210.The current adjustment circuit 250 shown in FIG. 8 is an example. Thecurrent adjustment circuit 250 may also be implemented in otherconfigurations.

The slope-compensated inductance current is provided to the drivecontrol circuit 230, for example to the PWM circuit 233 for pulse widthmodulation, so as to output a drive signal Sd. The circuit adjustmentcircuit 250 and the drive control circuit 230 form a current loop. Whenthe input voltage Vin changes, a current in the current loop changessubstantially immediately or sufficiently quickly, thus the duty cycleof the voltage conversion circuit is adjusted, so as to adjust theoutput voltage.

FIGS. 9A-9D illustrate examples of simulation results of voltageconversion using the voltage converter 600 of FIG. 8. The feedforwardcircuit 240 in the voltage converter in FIG. 8 has the same circuitstructure as that shown in FIG. 5. In FIGS. 9A-9D, signal waveforms offour monitoring points are shown. More particularly, a voltage waveformof the input voltage Vin is shown in FIG. 9A; a voltage waveform of theoutput voltage Vout is shown in FIG. 9B; a voltage waveform of thecompensation signal COMP obtained after frequency-compensation is shownin FIG. 9C; a current waveform of the feedforward current Sf output fromthe feedforward circuit 240 is shown in FIG. 9D.

In FIG. 9A, a horizontal axis is a time in microsecond, and a verticalaxis is a voltage value of the input voltage Vin in millivolt. As shownin FIG. 9A, the input voltage Vin has a voltage increase from 3 v to 3.5v at a time of 500 ms, and has a voltage decrease from 3.5 v to 3 v at atime of 710 ms.

In FIG. 9B, a horizontal axis is time in microsecond, and a verticalaxis is a voltage value of the compensation voltage Vout in millivolt,in which two curves are illustrated, i.e. curve CUR1 and curve CUR2. Thecurve CUR1 is an output voltage Vout obtained from a voltage conversionperformed by the voltage converter 600 in FIG. 8. The curve CUR2 is anoutput voltage Vout obtained from the voltage conversion performed bythe voltage converter 600 in FIG. 8 with the feedforward circuit 240removed. That is, the feedforward circuit 240 and the adder 231 areremoved from the voltage converter 600 in FIG. 8 and the error signal Seoutput by the feedback circuit is performed frequency compensationdirectly to be provided to the PWM circuit 233. It can be seen from FIG.9B that, during the voltage increase of the input voltage Vin, there isa notable increase in the curve CUR2 which is from 4.6 v to 4.635 v,whereas the increase in the curve CUR1 is notably reduced, which ismerely from 4.6 v to 4.61 v; during the decrease of the input voltageVin, there is a notable decrease in the curve CUR2 which is from 4.6 vto about 4.57 v, whereas the decrease in the curve CUR1 is notablyreduced, which is merely from 4.6 v to about 4.59 v. Therefore, whilethe feedforward circuit 240 is added into the voltage converter, theoutput voltage Vout can be relatively stably maintained at a targetvoltage of 4.6 v with a favorable linear state, even if the inputvoltage Vin changes.

In FIG. 9C, a horizontal axis is a time in microsecond, and a verticalaxis is a voltage value of the compensation signal COMP in volt, inwhich two curves are illustrated, i.e. curve CUR3 and curve CUR4. Thecurve CUR3 is a compensation signal COMP in the case of implementingvoltage conversion by the voltage converter 600 in FIG. 8. The curveCUR4 is a compensation signal COMP in the case of removing thefeedforward circuit 240 from the voltage converter 600 in FIG. 8.

It can be seen from FIG. 9C that during the increasing period of theinput voltage Vin from 500 ms to 510 ms, the CUR3 with the feedforwardcircuit 240 included quickly decreases during the increasing period from500 ms to 510 ms to compensate for an increase of the input voltage;whereas a descending process of the CUR4 without the feedforward circuit240 continues from 500 ms until 530 ms, and increases during a periodfrom 530 ms to 550 ms due to too much decrease, i.e. the compensationprocess in the curve CUR4 continues from 500 ms until 550 ms, whichgreatly lags behind the timing of 510 ms.

It can be further seen from FIG. 9C that, during the decreasing periodof the input voltage Vin from 710 ms to 720 ms, the CUR3 with thefeedforward circuit 240 included quickly increases during the decreasingperiod from 710 ms to 720 ms to compensate for an increase of the inputvoltage; whereas an increasing process of the CUR4 without thefeedforward circuit 240 included continues from 710 ms until 730 ms, anddecrease during a period from 730 ms to 760 ms due to too much increase,i.e. a compensation process in the curve CUR4 continues from 710 msuntil 760 ms, which greatly lags behind the timing of 720 ms. Thus,after the feedforward circuit 240 has been added, the voltage converterhas favorable transient response characteristic when the input voltageVin changes.

In FIG. 9D, a horizontal axis is a time in microsecond, and a verticalaxis is a current value of the feedforward signal Sf in microamp. Asshown in FIG. 9D, during the increasing period of the input voltage Vinfrom 500 ms to 510 ms, a current value of the feedforward signal Sfgenerates a decrease pulse, which makes the voltage of the compensationsignal COMP immediately decrease and the current of the inductor 211 inthe voltage conversion circuit 210 quickly reduce, so as to reduce anincrease of the output voltage Vout caused by an increase of the inputvoltage Vin. During the decreasing period of the input voltage Vin from710 ms to 720 ms, the current value of the feedforward signal Sfgenerates an increase pulse, which makes a voltage of the compensationsignal COMP immediately increase and the current of the inductor 211 inthe voltage conversion circuit 210 quickly increase, so as to reduce adecrease of the output voltage Vout caused by the decrease of the inputvoltage Vin.

FIG. 10 is a flowchart illustrating a voltage conversion method 1000according to an embodiment of the present disclosure. The voltageconversion method 1000 may be applied to the voltage converter as shownin FIG. 2, and can be referred to the above description in connectionwith FIGS. 2 to 5. The voltage converter may include a voltageconversion circuit, a feedback circuit, a drive control circuit and afeedforward circuit. The voltage conversion circuit and the feedforwardcircuit receive the input voltage. The voltage conversion circuitimplements voltage conversion to the input voltage and output an outputvoltage, which is then provided to the feedback circuit. As shown inFIG. 10, the voltage conversion method 1000 may comprise steps S1010 toS1050.

In the step S1010, the input voltage is converted into a desired outputvoltage by the voltage conversion circuit. The converted output voltagemay be either higher or lower than the input voltage.

In S1020, the output voltage is compared with a reference voltage by thefeedback circuit, and an error signal is output. The reference voltagecorresponds to a target voltage to be output by the voltage converter.The error signal is used for indicating a difference between the outputvoltage and a target voltage to be output by the voltage converter.

In S1030, a feedforward signal for the input voltage is generated by afeedforward circuit based on the input voltage, and the feedforwardsignal can be, for example, a pulse signal having tendency of changeopposite to a change of the input voltage. For example, when the inputvoltage increases from a first voltage to a second voltage, the secondvoltage is higher than the first voltage, and feedforward signal maygenerate a decrease pulse; when the input voltage decreases from thesecond voltage to the first voltage, the feedforward signal may generatean increasing pulse. When the input voltage stays unchanged, thefeedforward circuit outputs a constant feedforward signal.

In S1040, a drive signal for driving the voltage conversion circuit isgenerated by the drive control circuit based on the feedforward signaland the error signal. The drive signal is used for controlling acharging operation and a discharging operation of the voltage conversioncircuit.

Furthermore, in the case where the voltage converter to which thevoltage conversion method 1000 is applied operates in a current mode,the voltage converter further comprises a current adjustment circuit asshown in FIG. 6, and the voltage conversion method 1000 may furthercomprise: sensing a inductance current of the voltage conversion circuitby the current adjustment circuit, and generating an indication signalfor indicating the inductance current based on the sensed inductancecurrent, which is then provided to the drive control circuit (S1050), asshown with a dotted line in FIG. 10. Since the inductance current in thevoltage conversion circuit directly affects the output voltage of thevoltage converter, the indication signal for indicating the inductancecurrent can be used for driving the voltage conversion circuit, so as toobtain a desired output voltage.

Accordingly, in S1040, a drive signal for driving the voltage conversioncircuit is generated by the drive control circuit based on thefeedforward signal, the error signal and the indication signal forindicating the inductance current.

In the case where the voltage conversion circuit in the voltageconverter is a buck conversion circuit or a boost-buck conversioncircuit, the output voltage may be lower than the input voltage. In thiscase, the feedforward circuit may be unable to detect a voltage value ofthe input voltage. Accordingly, before a feedforward signal for theinput voltage is generated by using the feedforward circuit based on theinput voltage in S1030, it may be further included in the voltageconversion method 1000 where the input voltage is divided and a reducedvoltage lower than the input voltage is obtained (S1060), as shown inFIG. 10. Thereafter, in S1030, a feedforward signal for the inputvoltage is generated based on the reduced voltage. The feedforwardsignal can be, for example, a pulse signal having opposite tendency ofchange when the input voltage changes.

The particular structure of the voltage converter in according to theembodiment of the present disclosure, to which the voltage conversionmethod 1000 is applied, may refer to the illustration in FIG. 2 to FIG.8 and the relevant descriptions. An order of the steps in FIG. 10 is anexample, and may not constitute limitation to the embodiment of thepresent disclosure.

In the voltage conversion method 1000 according to the embodiment of thepresent disclosure, the jumping change of the input voltage is quicklyconverted into a feedforward signal by using a feedforward circuit tocontrol the operation of the voltage converter, which improves atransient response characteristic of the voltage converter. Accordingly,the output voltage can be maintained in favorable linear state even ifthe input voltage changes.

Those skilled in the art may clearly understand that, for convenienceand simplicity of the description, the specific implementations of themethod embodiment described above can refer to corresponding process inthe preceding product embodiments.

Those skilled in the art can realize that, devices and algorithm stepsof the examples described with reference to the embodiments disclosed inthe disclosure may be implemented through electronic hardware, or acombination of the electronic hardware and software. As for eachspecific application realization, a person skilled in the art can usedifferent manner to implement the described functions, but suchimplementations should not be considered to go beyond the scope of thepresent disclosure.

Principles and advantages of technical solutions described above areapplicable to any voltage converter. The voltage converter can beapplied in a variety of electronic apparatus. The electronic apparatusmay include, but is not limited to, a consumer electronic product, aportion of a consumer electronic product, an electronic test equipmentetc. The consumer electronic product may include, but is not limited to,a smart phone, a TV, a tablet computer, a monitor, a personal digitalassistant, a camera, an audio player, a memory etc. A portion of theconsumer electronic product may include a multi-chip module, a poweramplifier module, a voltage converter etc.

For example, FIG. 11 shows a block diagram of a portable electronicdevice 1100 that can benefit from one or more features as describedherein. Such a portable electronic device can include, for example, apower management circuit 1102 configured to provide a first voltage foroperation of the portable electronic device. Such a first voltage can bebased on, for example, a battery voltage provided by a battery. Theportable electronic device 1100 can also include a functional component1106 having an electrical load and configured to utilize a secondvoltage. Such a functional component can be any circuit, device, or anycombination thereof, configured to facilitate operation of the portableelectronic device 1100. Non-limiting examples of such a functionalcomponent are described in reference to FIG. 12.

Referring to FIG. 11, the portable electronic device 1100 can furtherinclude a voltage converter 1104 configured to convert the first voltageto the second voltage, to thereby allow operation of the functionalcomponent 1106. Such a voltage converter can include one or morefeatures as described herein.

In some implementations, the portable electronic device of FIG. 11 canbe a radio-frequency (RF) device such as a wireless device. In someembodiments, such a wireless device can include, for example, a cellularphone, a smart-phone, a hand-held wireless device with or without phonefunctionality, a wireless tablet, etc.

FIG. 12 depicts an example wireless device 1200 having one or moreadvantageous features described herein. In such a wireless device, oneor more functional components can include respective electrical load(s),and be provided with an appropriate operating voltage by one or morevoltage converters (depicted as 1204) having one or more features asdescribed herein.

For example, a power amplifier (PA) 1206 b can be provided with a supplyvoltage from the voltage converter 1204 to facilitate amplification ofan RF signal to be transmitted. In some embodiments, such a PA can bepart of a PA module (PAM) 1212.

In another example, a light-emitting diode (LED) illumination unit 1206a can be provided with a supply voltage from the voltage converter 1204to facilitate operation of a camera module 1210. It will be understoodthat other functional component(s) of the wireless device 1200 can alsoutilize the voltage converter 1204.

In the example wireless device 1200 of FIG. 12, a power managementcircuit 1202 can be provided. Among others, such a circuit can providean input voltage for the voltage converter 1204, based on power providedby a battery 1228.

In the example wireless device 1200 of FIG. 12, the PAs (e.g., 1206 b)can receive their respective RF signals from a transceiver 1232 that canbe configured and operated to generate RF signals to be amplified andtransmitted, and to process received signals. The transceiver 1232 isshown to interact with a baseband sub-system 1230 that is configured toprovide conversion between data and/or voice signals suitable for a userand RF signals suitable for the transceiver 1232.

The baseband sub-system 1230 is shown to be connected to a userinterface 1222 to facilitate various input and output of voice and/ordata provided to and received from the user. The baseband sub-system1230 can also be connected to a memory 1224 that is configured to storedata and/or instructions to facilitate the operation of the wirelessdevice, and/or to provide storage of information for the user.

In the example wireless device 1200, outputs of the PAs can be matchedby a matching network and routed to an antenna 1244 via their respectiveduplexers 1240 and a band-selection switch 1242. In some embodiments,each duplexer can allow transmit and receive operations to be performedsimultaneously using a common antenna (e.g., 1244). In FIG. 12, receivedsignals are shown to be routed to “Rx” paths that can include, forexample, one or more low-noise amplifiers (LNAs).

The above described are only specific example implementations of thepresent disclosure, but the scope of protection of the presentdisclosure is not limited thereto, and any changes and alternatives thatcan be easily conceived by those skilled in the art should beencompassed within the protection scope of the present disclosure.

1. A voltage converter comprising: a voltage conversion circuitconfigured to convert an input voltage to an output voltage; a feedbackcircuit configured to generate an error signal based on the outputvoltage and a reference voltage, the error signal utilized to adjust theoutput voltage; a feedforward circuit including a current mirror andconfigured to generate a feedforward signal based on an operation of thecurrent mirror resulting from a change in the input voltage; and a drivecontrol circuit configured to generate a drive signal for the voltageconversion circuit based at least in part on the feedforward signal. 2.The voltage converter of claim 1 wherein the feedforward circuit furtherincludes an input node having a voltage representative of the inputvoltage.
 3. The voltage converter of claim 2 wherein the current mirrorof the feedforward circuit includes first and second transistorsarranged in a current-mirror configuration and coupled to the inputnode, such that the change in the input voltage results in a change in acurrent flowing through one of first and second transistors, andtherefore a corresponding change in a current flowing through the othertransistor, the feedforward signal being based on the change in thecurrent flowing through the other transistor.
 4. The voltage converterof claim 3 wherein each of the first and second transistors includes asource, a drain, and a gate, the gates of the first and secondtransistors being connected.
 5. The voltage converter of claim 4 whereinthe feedforward circuit further includes a capacitance implementedbetween the input node and a node between the gates of the first andsecond transistors.
 6. The voltage converter of claim 3 wherein each ofthe first and second transistors is a P-type transistor.
 7. The voltageconverter of claim 6 wherein the current mirror is configured such thata decrease in the input voltage at the input node results in an increasein the current flowing through the other transistor.
 8. The voltageconverter of claim 3 wherein each of the first and second transistors isan N-type transistor.
 9. The voltage converter of claim 8 wherein thecurrent mirror is configured such that an increase in the input voltageat the input node results in an increase in the current flowing throughthe other transistor.
 10. The voltage converter of claim 1 wherein thedrive control circuit is configured such that the drive signal is alsobased on the error signal.
 11. The voltage converter of claim 10 whereinthe error signal is representative of a difference between the outputvoltage and the reference voltage which is representative of a desiredtarget value of the output voltage.
 12. The voltage converter of claim11 wherein the feedback circuit includes a voltage divider configured toobtain a portion the output voltage.
 13. The voltage converter of claim12 wherein the feedback circuit further includes an operationalamplifier configured to receive the portion of the output voltage andthe reference voltage to generate the error signal.
 14. The voltageconverter of claim 1 wherein the feedforward signal includes one or morepulses having a changing tendency opposite to the change in the inputvoltage.
 15. A method for operating a voltage converter, the methodcomprising: operating a voltage conversion circuit to convert an inputvoltage to an output voltage; generating an error signal with a feedbackcircuit based on the output voltage and a reference voltage, the errorsignal allowing adjustment of the output voltage; generating afeedforward signal with a feedforward circuit having a current mirror,based on an operation of the current mirror resulting from a change inthe input voltage; and providing a drive signal for the voltageconversion circuit based at least in part on the feedforward signal. 16.A portable electronic device comprising: a power management circuitconfigured to provide a first voltage; a functional component having anelectrical load and configured to utilize a second voltage; and avoltage converter including a voltage conversion circuit configured toconvert the first voltage to the second voltage, the voltage converterfurther including a feedback circuit configured to generate an errorsignal based on the second voltage and a reference voltage, the errorsignal utilized to adjust the second voltage, the voltage converterfurther including a feedforward circuit having a current mirror andconfigured to generate a feedforward signal based on an operation of thecurrent mirror resulting from a change in the first voltage, the voltageconverter further including a drive control circuit configured togenerate a drive signal for the voltage conversion circuit based atleast in part on the feedforward signal.
 17. The portable electronicdevice of claim 16 wherein the portable electronic device includes awireless device.
 18. The portable electronic device of claim 17 whereinthe functional component includes an amplifier or an illuminationdevice.
 19. The portable electronic device of claim 18 wherein theamplifier includes a power amplifier.
 20. The portable electronic deviceof claim 18 wherein the illumination device includes a light-emittingdiode.